added git ignore file
Added new file to keep fraction rules.
added predicates for fraction numerator and denom
added rule for summing fractions with same denominator
add fractions different denominators; works, but looks horrendous
Add fractions with different divisors, second version.
added rule for multiplying fractions
added divide by fraction rule
made divide by fraction more general
cleaned up eqn_solver file and added comments
added sum fractions (diff denominators); it's an ugly rule, needs refactoring
added README, no content yet